The Intel® Atom™ E6xx System on a Chip (SoC) and ADI Engineering Inc’s (1) Input/Output Hub-less design approach, combined with third party software yields low cost, small footprint, system alternatives employing the x86 family. The software abundance from more than 30 years of software developments, including Open Source initiatives, extends the large base of software available for members of the x86 family, including the E6xx processor. An 802.11n-to-HDMI streaming HD media player is implemented by ADI Engineering using customized logic, the Intel boot loader technology, and the E6xx processor. We’ll examine how narrowly focused hardware platforms can be combined with an Operating System and applications software to realize high-function deeply embedded systems.
Steve Yates, President of ADI Engineering, defines a “thin” device as “perform[ing] a single fixed function, and must meet stringent requirements for cost, size, power consumption, ease-of-use, and reliability.” ADI Engineering’s approach to creating thin clients employing the Intel® Atom™ E6xx processor was detailed in a recent blog. But how do we use Yates’ definition to guide our design process?
Consider an 802.11n to HDMI video streaming player, there is relatively little in the way of requirements outside the input of the Internet Protocol media source and the HDMI video output. This reduction in media and control sources means that the streaming media player is an excellent candidate for using a Thin Device design.
The standard IOH contains control for several devices that are not required for the media player Thin Device.
A dedicated streaming media player does not need an interface to a mass storage device based on the Serial Advanced Technology Attachment specification (SATA). Practically, a media player does not need to store large quantities of data locally. Nor does a media player need USB host ports, an RS232 port, or a touch screen interface. Also superfluous are Universal Asynchronous Receiver Transmitters (USARTs), a real time clock, discrete I/O, and the trusted platform module. Of course, small changes in system specifications may alter these decisions. Where one design team chooses to drop the trusted platform module another may decide that for reasons of a closed system integrity. Such a decision may require that the module should be included.
ADI’s conceptual media player has a simplified block diagram compared to a generic IOH-based design.
The ADI Thin Application approach replaces the Intel Atom IOH with a reduced feature set chip. Chief among the required features is a way to bootload the CPU. This may be accomplished by employing the Intel Boot Loader Kit, BLDK or licensing a version of the modified Boot Loader from a vendor like ADI.
Building the application environment depends to a large extent on the type of application desired. The application environment is often driven by a desire to maintain future flexibility as a hedge against unexpected feature demands. But that degree of flexibility comes at a cost that the target environment may not be able to support.
According to Yates’ definition of a thin device, cost may be (and often is) one of the critical considerations. A systems decision will affect software choices for any embedded device, especially a decision to not include mass storage. For many thin applications cost control means eliminating a degree of flexibility. This “reduced” feature set may mean that the application software may not rely on typical BIOS runtime facilities. Instead of an off-the-shelf BIOS, developers must create a customized BIOS replacement. Custom-developed BIOS replacements are available from American Megatrends, Inc (2), Insyde Software (3), Nanjing Byosoft Co. Ltd (4) and Phoenix Technologies, Ltd(5).
While full BIOS-replacement software may be the technically safest choice, in many cases, like the streaming media player, the added cost of the BIOS licensing fee and Non-Recurring Engineering (NRE) costs are often more that the final product can absorb and still meet its cost goals.
Engineers of lower cost products often choose to eliminate the cost of a full BIOS since much of it may not be used in the final product. In this case, there remains a decision to be made: whether to use a bare-bones kernel, use an off-the-shelf RTOS, or to implement a purpose-designed RTOS. A kernel manages the hardware resources. For the streaming media player we have limited external devices: an 802.11n transceiver interface, the display control, and possibly a small number of control inputs such as for a pointing device. Commercially available RTOSes from Green Hills Software (6), Wind River Systems (7), and QNX (8) may suit a specific thin application. More fully featured RTOSes like TenAsys (9) will likely be viable choices for more capable systems.
FreeRTOS straddles the ground between developing a kernel and adopting a full commercial RTOS. FreeRTOS is downloadable at no cost, but there is work to make the RTOS work on the selected hardware. Industry associations have lead to the creation of two other variants of FreeRTOS, SafeRTOS and OpenRTOS. It is possible to obtain validation results for versions of FreeRTOS, but the RTOS itself is designed for use on microcontrollers with a single processor core. Those limitations may make FreeRTOS a good starting point for developing a purpose-built RTOS, but may make it unsuitable for use in more advanced Atom-based thin devices.
No software environment is complete without development tools. The question is whether there is any restriction on the use of standard, available, development tools when creating a thin device. The answer to this question is “no.” Thin devices are created using a standard Atom processor and Atom software and debug tools. Even JTAG and similar probes can be used with the thin device.
Atom-based thin applications and thin devices offer unprecedented flexibility to meet cost and performance constraints.
Where does the new Atom E6xx options for cost control fit into your future product plans?
- ADI Engineering is an Associate member of the Intel Embedded Alliance
- American Megatrends, Inc. is an Affiliate member of the Intel Embedded Alliance
- Insyde Software is an Affiliate member of the Intel Embedded Alliance
- Nanjing Bysoft Co., Ltd is a General member of the Intel Embedded Alliance
- Phoenix Technologies, Ltd is an Affiliate member of the Intel Embedded Alliance
- Green Hills Software is an Affiliate member of the Intel Embedded Alliance
- Wind River Systems is an Associate member of the Intel Embedded Alliance
- QNX Software Systems is an Associate Member of the Intel Embedded Alliance
Roving Reporter (Intel Contractor)
Intel® Embedded Alliance